1. Field of the Invention
A tie bar assembly for use in a vehicle useful for controlling powertrain movements around and perpendicular to the powertrain roll axis and to isolate powertrain generated vibrations.
2. Description of the Prior Art
The tie bar assemblies of the type to which the subject invention pertains, attach to a vehicle chassis and to a powertrain component and dampen vibrational forces from the powertrain component. One such tie bar assembly is illustrated in U.S. Pat. No. 4,887,801 A to Wolf et al. wherein a housing having a tubular shape is disposed about a central axis. This invention includes a rear unit disposed annularly about the central axis in the housing and includes a cylindrical rear inner insert and a rear outer insert. A rear web interconnects the rear inserts for allowing axial movement of the rear inner insert relative to the rear outer insert. Additionally, a front unit is disposed annularly about the central axis in the housing and includes a cylindrical front inner insert and a front outer insert. A front web interconnects the front inserts for allowing axial movement of the front inner insert relative to the front outer insert. A connecting rod is disposed along the central axis and is attached to the rear inner insert and the front inner insert. This patent and U.S. Patent Application No. 2009/0090586 A1 by Lopez, Jr. et al. disclose a pole sub-assembly that is disposed annularly about the central axis. In Wolf et al. the pole sub-assembly is disposed between the rear unit and the front unit. The pole sub-assembly and the units define a front fluid chamber extending annularly about the central axis and a rear fluid chamber extending annularly about the central axis. Lopez, Jr. et al. discloses a magneto-rheological fluid contained within a front fluid chamber and a rear fluid chamber. Additionally, a plurality of fluid orifices are disposed through the pole sub-assembly for fluid flow of the magneto-rheological fluid between the front fluid chamber and the rear fluid chamber. The Lopez, Jr. et al. pole sub-assembly also includes an outer pole member extending annularly about the central axis and an inner pole member extending annularly about the central axis and radially aligned with the outer pole member. Lopez, Jr. et al. also shows a pole sub-assembly that includes a rear end plate disposed on one side of the inner pole member and includes a front end plate disposed on the opposite side of the inner pole member. U.S. Patent Application 2012/0091639 A1 by Lee et al. discloses another similar assembly for use in a vehicle that includes separate fluid chambers containing a fluid wherein a plurality of fluid orifices allow fluid flow between the fluid chambers.
However, the prior art tie bars include an elastomer diaphragm causing complete hydraulic separation between the front and rear fluid chambers. Additionally, some of the prior art tie bars do not include a cushion to limit movement of the inner inserts against the pole sub-assembly, or only include a cushion on either the front insert or rear insert.